1. Field of the Invention
The present invention relates to an in-plane switching active matrix liquid crystal display (LCD) apparatus that has improved transmissivity.
2. Description of the Related Art
FIG. 1 is a cross-sectional view showing the operation of a conventional in-plane switching LCD apparatus, and FIG. 2 is a cross-sectional view schematically depicting a pixel of an in-plane switching LCD apparatus of the related art. In the related art in-plane switching LCD apparatus as shown in FIG. 2, a liquid crystal layer 102 is provided between a pair of transparent substrates 101a, 101b, and pectinate pixel electrodes 103 and common electrodes 104 are disposed on the transparent substrate 101a in the aperture of the pixel.
When an image is displayed in the related art in-plane switching LCD apparatus thus configured, different voltages are applied between the pixel electrodes 103 and the common electrodes 104 to generate a horizontal electric field substantially parallel to the substrate surface between these electrodes, and this horizontal electric field causes the liquid crystal molecules between the electrodes to rotate within a plane substantially parallel to the substrate surface. Since images are displayed through rotation of the liquid crystal molecules within a plane parallel to the substrate surface, the viewing angle is not dependent on the rise angle of the liquid crystal molecules, which allows for a display with a wider viewing angle free of grayscale inversion.
The LCD apparatus disclosed in Japanese Laid-open Patent Application No. 2004-354407 (hereinafter Patent Document 1) is an example of a conventional in-plane switching LCD apparatus such as is described above. Patent Document 1 discloses an example of a configuration in which pixel electrodes and common electrodes are formed on one of a pair of opposing substrates, first continuous solid electrodes are provided via an insulating film on the bottom layers of the pixel electrodes and common electrodes on this substrate, and second continuous solid electrodes are formed on the liquid crystal layer side of the other substrate opposing the first substrate.
When an image is displayed in the conventional LCD apparatus having this configuration disclosed in Patent Document 1, voltages are applied between the pixel electrodes and the common electrodes, and the liquid crystal molecules are driven under the action of an electrical field substantially parallel to the substrate surface. In the initial stage of the image non-display state, voltage is applied between the first continuous solid electrodes and the common and pixel electrodes, as well as between the second continuous solid electrodes and the common and pixel electrodes without being applied between the pixel electrodes and the common electrodes. This generates a vertical electric field and raises the liquid crystal molecules, displaying a black screen. Following the initial stage of the image non-display state, the electrodes are brought to the same electric potential, whereby the pixel interiors lose their electric field, the raised liquid crystal molecules revert to their initial alignments, and the black display remains. Generating a vertical electric field in the initial stage of the image non-display state makes it possible to reduce rise-and-fall response time, to inhibit blurring of moving images, and to provide high-quality moving images.
However, the conventional technology described above has the following problems.
In a conventional in-plane switching active matrix LCD apparatus, since pectinate electrodes are formed inside the pixels on one of the substrates, the apertures are inevitably smaller, causing transmissivity to be reduced. In particular, there have been problems with low transmissivity in LCD apparatuses because the liquid crystal molecules on the electrodes cannot be driven.